DESCRIPTION: The objective of this research is to investigate the mechanism of genotoxicity, mutagenicity, and DNA repair of the DNA adducts formed by the anticancer drug, mitomycin C. To accomplish these goals, Dr. Basu proposes to use a combination of chemical synthesis and recombinant DNA technology to construct viral DNA molecules that would contain, at specific genome locations, the known DNA adducts (which include two monoadducts and an interstrand cross-link) formed by mitomycin C. The resultant site-specifically modified genomes will be introduced into bacterial cells, where the single DNA lesion will be acted upon by the replication and repair system of the cell. He will determine the relative genotoxicity potential, the amount and type of mutagenesis induced by each adduct. Host cells with different genetic background will be used to determine the host genes that are responsible for repair and for mutagenesis of these adducts. A major objective of this work is to investigate the mechanism of repair of mitomycin DNA cross-link. A comparative assessment of the biological effects of the cross-link and the two major monoadducts is another aim of this research. Subsequently, the genotoxicity and mutagenicity studies on these adducts will be carried out in mammalian cells by using a site-specifically modified shuttle vector. This experimental design will be able to establish the formal rules that relate the structure of the DNA lesion with its biological effects. In addition, the biochemical pathways by which these damages in DNA are repaired in bacterial and mammalian cells will be elucidated.